How to go to Mutianyu Great Wall from Ming tomb?

It is not very convenient by public transportation because you need to transfer for two times. A one-day trip of Mutianyu and Ming Tombs is not possible unless you charter a minibus, which costs about CNY 1,000.
Actually, it is recommended to take a one-day Badaling-Ming Tombs trip. You can take train S2 at BJ North Railway Station directly to the wall. After, take bus no.879 to the Ming Tombs.
To get to the train station, you can take subway line 5 at Dengshikou Station and transfer to line 2 at Yonghe Lamasery Station. Get off at Xizhimen Station and walk northwards.

Thx for ur reply. How long from novotel to Badaling using subway line 2 north railway ? Or any car rent you could recomend me?

Going to the train station via subway is very convenient. It takes around an hour by S2 train to Badaling from the North Station. For car renting, the round trip may cost CNY400-500. You can ask your hotel to have one for you.